1. Field of the Invention
This application is filed under 35 U.S.C. 371 and based on PCT/EP98/04564, filed Jul. 21, 1998.
This invention relates to an enzyme capable of hydrolytically cleaving mixed glucans, which are linked alternately by 1,3- and 1,4-xcex2-glucosidic bonds, into oligosaccharides and to the microorganism which forms this enzyme.
Enzymes such as these belong to the class of endo-1,3-1,4-xcex2-D-glucan4-glucanohydrolases (EC 3.2.1.73; lichenases) or endo-1.3-xcex2-D-glucosidases (EC 3.2.1.39; laminarinases). For the purposes of the present invention, an enzyme of this type is referred to herein as xcex2-glucanase or beta-glucanase.
2. Discussion of Related Art
Polymeric mixed glucans of the type mentioned above are present in varying amounts in virtually all cereal products. Enzymes capable of cleaving them are required above all in the food, beverage and animal feed industries, the textile industry and in the processing of starch (R. Borriss xe2x80x9cxcexc-Glucan-spaltende Enzymexe2x80x9d, in H. Ruttloff: xe2x80x9cIndustrielle Enzymexe2x80x9d, Chapter 11.5, Behr""s Verlag, Hamburg (1994)). One of the most important applications of xcex2-glucanases is in the beverage and brewing industries where enzymes such as these are used for degrading malt and barley xcex2-glucan. The enzymes used for this purpose normally emanate from Bacillus subtilis, as described for example in German patent DD 226 012 A1, or from Bacillus amyloliquefaciens, although xcex2-glucanases from other microorganisms, for example Achromobacter lunatus, Athrobacter luteus, Aspergillus aculeatus, Aspergillus niger, Disporotrichum dimorphosporum, Humicola insolens, Penicillium emersonli, Penicillium funiculosum or Trichoderma reesei, are also known. A commercial product intended for use in the brewing industry is marketed, for example, under the name of Cereflo(copyright) (manufacturer: Novo Nordisk A/S).
Hitherto known xcex2-glucanases have pH optima in the weakly acidic to neutral range, so that their use is confined to processes which are carried out at those pH values. The problem addressed by the present invention was to extend the field of application of xcex2-glucanases and to develop a xcex2-glucanase which would be sufficiently stable under alkaline conditions for use in industrial processes carried out under conditions.